TabView tabTextColor explanation could be expanded

[Mottokrosh]

Hi folks,

In my project I wanted to change the icon of a tab to a multi-colored one (well, essentially one color and a red dot), when I noticed that the icon instead became monochrome, and reflected the tabTextColor (or selectedTabTextColor) color set. This is on iOS at least.

Basically by default, on iOS, tabTextColor and selectedTabTextColor affect text color and icon color. Setting the iosIconRenderingMode property on TabView to alwaysOriginal changes this behavior, so that only text is affected. (In this case it's up to the developer to change the icon themselves when selected of course.)

I think it would be nice to make this behaviour explicit in the documentation.